Fair Value Measurements - Fair Value by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	$ 108,392	$ 104,711
Over One Year Through Five Years	67,142	93,852
Over Five Years	0	0
Total	175,534	198,563
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	38,899	22,550
Over One Year Through Five Years	11,681	30,114
Over Five Years	0	0
Total	50,580	52,664
Yankee bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	6,103	4,150
Over One Year Through Five Years	1,852	2,010
Over Five Years	0	0
Total	7,955	6,160
Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	6,971	14,041
Over One Year Through Five Years	0	3,489
Over Five Years	0	0
Total	6,971	17,530
Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	0	0
Over One Year Through Five Years	11,692	12,229
Over Five Years	0	0
Total	11,692	12,229
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	9,185	17,690
Over One Year Through Five Years	0	0
Over Five Years	0	0
Total	9,185	17,690
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	23,250	20,868
Over One Year Through Five Years	4,803	6,667
Over Five Years	0	0
Total	28,053	27,535
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	23,984	25,412
Over One Year Through Five Years	37,114	39,343
Over Five Years	0	0
Total	$ 61,098	$ 64,755